1. Potential and need for soil tillage research;Larson,1967
2. Effect of tillage on plant growth as influenced by soil organisms;McCalla,1967
3. Nutrient relationships and fertilizer placement as affected by tillage;Holt,1967
4. Influence of tillage practices on clod size, porosity and water retention;Bushan;Ind. J. agric. Sci.,1973
5. Minimum tillage for soil and water conservation;Free;Agric. Engng,1960